JPS58108565A - Developing device - Google Patents

Abstract

PURPOSE:To obtain sharp and stable image without the adhesion of toner to a nonimage-part by generating an alternating electric field between an electrostatic holding element and a toner carrier under magnetic force from a developer supporting element while supplying toner to the electrostatic holding member at a low speed to oscillate toner particles. CONSTITUTION:A developer carrier 2 to carry insulating magnetic toner is set up to the same or lower speed as/than the moving speed of an electrostatic holding element 1 and AC bias voltages 10, 11 at least are applied to the carrier 2. This method is based upon the fact that there are conditions to oscillate toner particles in a magnetic toner layer on the developer carrier 2 by said alternating electric field under the condition of carriage of magnetic bias instead of ordinary development by magnetic brush and as the result to form sharp image only in an image part and image part and to actually prevent toner adhesion to the nonimage part.

Description

[Detailed Description of the Invention] The Tei invention is an electrostatic recorder for electrophotographic copying devices, etc. This relates to a developing device used in the device, and more particularly, an improvement to the developing device that uses insulating magnetic toner to obtain a visible image with excellent image clarity and no blurring and rich in quality. Regarding.

Conventionally, a one-component developer is used, and a 5 mm holder is placed opposite to the electrostatic image holder with a required gap, and is faced with a gap that flies in an alternating electric field of I KHz or less. A high-frequency pulse bias is applied to the gap between the electrostatic image holder and the developer carrier, so that the developer adheres to the image area of the electrostatic image holder, but not to the non-image area. The technique is also known. (For example, U.S. Patent No. 3
8909298 Ming Susho 1, WiJ3866574 specification, p@38934111 specification, etc.) All of these known examples use a - line segment dry developer,
In order to prevent such developer (toner) from adhering to non-image areas, the electrostatic image holder and the developer carrier are made to face each other with a gap sufficient for toner flight. The configuration is adopted. In this method, a thin layer of toner is formed on the developer carrier to limit the amount of toner that adheres to the electrostatic image carrier. The moving speed of the toner and developer carrier needs to be at least the same speed as the electrostatic image carrier. In a developing device that visualizes an electromagnetic image by bringing two thinner layers into contact with each other, a developer carrier carrying the insulating magnetic toner,
A developing device is provided, which is set to a moving speed that is the same as or slower than the moving speed of the electrostatic image carrier, and at least an alternating current bias voltage is applied to the m developer carrier. Compared to non-contact development methods such as jumping development, this method allows high-speed development because a larger amount of toner is supplied to the electrostatic latent image on the electrostatic image holder. (increased to electrostatic latent image like non-contact development method)
Since there is no need for the toner to move along the electric field from the facing state, low potential development is possible.

(fine) Since there is no need for the toner to fly, there is less toner scattering. Since it is sufficient to supply a large amount of toner, the setting of the image developer regulating section can be relaxed. (V) Although it has the advantage that even if there is a transport failure due to slight clogging in the toner regulating section, the amount of toner supplied is large, so it is unlikely to affect the development, it is easy to bleed during the middle power ( 11) There was a large gap in which the developer regulating section was clogged. Insulating toner, in particular, has the great advantage of being transferable to paper, but the above-mentioned drawbacks are also noticeable. As this fg #8 is insulating), it has a charge, so the residual potential of the non-ms part on the electrostatic image holder, the mirror image force in the W4 recording medium regulating part, the m charging of the fist, etc. Another reason is that it tends to adhere to non-image areas and developer regulating areas. In contrast, in the former case, a means for removing capri using magnetic force is generally used as a capri removal means. Although it is possible to remove the capri using a strong magnetic bias, the toner adheres to the edges and low potential areas of the ceramic image 11 in a scattered state, resulting in an image lacking in sharpness. ing.

On the other hand, if a strong intake force is used during development, the above-mentioned sharpness can be improved, but the disadvantage is that the image quality in the development direction deteriorates due to toner scattering and the intake force in the development direction. Furthermore, although the toner regulation conditions in the developer regulation section have been relaxed, the distance between the sleeve and the developer is 0.1 to 0.
5 m II! The phenomenon of pinching is similar, and when the toner conveyance speed is high, toner agglomeration is likely to occur in the developer regulating section.

According to the present invention, in a developing section that visualizes an electrostatic image by bringing a single layer of magnetic toner into contact with an electrostatic image holder, the above-mentioned toner conveys the toner at a low speed under a magnetic bias condition from a developer carrier. The developing device is characterized in that it prevents the agglomeration of toner (in the developer regulating section) by applying the alternating electric field as an electric bias to the developer carrier, and sharpens the image. I decided to provide it.

That is, the present invention vibrates toner particles in a single layer of magnetic toner on a developer carrier by using the above-mentioned alternating electric field under conditions where the magnetic bias is limited to conveyance rather than development using a conventional magnetic brush, so that only the image area is produced. This was done based on the fact that there is a condition in which a sharp image can be formed and toner does not substantially adhere to non-image areas.

Hereinafter, the present invention will be explained in detail using the drawings.

The first wJ shows a cross section tII diagram of an embodiment of the present invention. In the figure, the drum-shaped electrostatic image holder l is rotating in the direction of the arrow, and in the developing area on the circumference, there is a plate that rotates in the same direction as the rotation direction of the electrostatic image holder l. The magnetic cylindrical sleeve 2 is 0. It is arranged with a quantity line of "s"=.

It is preferable that this gap is maintained at 0.1 to 1.0. The rotational speed of the cylindrical sleeve 2 is approximately 11 m degrees from the circumferential speed of the electrostatic image holder 1, and the cylindrical sleeve 2 is rotationally driven in the direction of the arrow by a known driving means. At this level, image deterioration due to the force of uptake into the developer carrier will not occur, and developer aggregation at the developer regulating portion will not occur.

- As an example, using a photoreceptor of 8. (also, the circumferential speed of the electrostatic image holder is 180/...C, and the outer diameter of the cylindrical sleeve 2 is 3.
The rotation speed was set at 05 mφ and 40 rpwr. The S photoreceptor was charged to 500 V using Corina charging, and a light pattern of an original image was irradiated thereon. The cylindrical sleeve 2 has a fixed magnetic field 3 inside, and the magnetized magnetic pole in the image area is 1200 Gauss, and the center thereof has a magnetic flux distribution of 800 Gauss. Generally, a magnetic flux density of 500 Gauss or more is required, and 1500 Gauss is sufficient.

There is a magnetic material inside the developer supply section °4'a! The average grain of Dannetite has a weight of 45mm! Contains 124 liters of insulating toner particles. Developer supply to toner 1
The lower opening of 14 has a replenishing roller 5.

Due to this rotation of the replenishment roller 5, the toner that has entered the recess S (not shown) provided on the surface of the replenishment roller 5 is transferred to the replenishment roller 5.
At the same time, the toner falls onto the developer 1 [6] and replenishes toner. After the toner in the developer chamber 6 is stirred by the scraper JL7, it adheres to the cylindrical sleeve 2 and is transported to the developing area. The developer thickness regulating blade 8 is for regulating the thickness of the toner adhering to the cylindrical sleeve 211IQ to a predetermined value, and the cleaning blade 9 is for removing the cina adhering to the cylindrical sleeve 2 after development. It is.

IO is an AC power supply for applying an AC voltage of 100Hz to 10 KHl to the cylindrical sleeve 2, and this power supply IO is applied to the cylindrical sleeve 2 through a protective paper fill! i! Aggressive. Regarding the hook between the cylindrical sleeve 12 and the magnet reel 3 shown in FIG. A system in which both rolls rotate in opposite directions, or a system in which only the magnet roll rotates once can be adopted.

Next, regarding the developing device exemplified in No. 1v4, a layer insulating toner is used and an alternating electric field is applied to the base body (earth potential) of the electrostatic image holder l and the cylindrical sleeve 2 acting as a developing electrode.
The development that occurs during the process and its effects will be described below.

As previously mentioned, insulative-component toners are susceptible to coupling, and a magnetic bias is used to prevent this. At this time, applying a DC electrical bias does not play an active role in sharpening the image. This is because the electrical DC bias only shifts the electrical balance of development, which is the voltage relationship between the electrostatic charge image and the cylindrical sleeve. Applying a Do bias will actually increase Capri. Embodiment 1E shows a case in which only M0 bias is applied and IIIRI is applied.

Honkaimei is characterized by sharpening the image by promoting development with an alternating electric field under magnetic bias, but the alternating electric field cannot be used without limit. The second panel shows the relationship between the surface potential of 8. a photoreceptor and the reflection density of an image transferred and fixed onto a transfer paper after development, as an example of an electrostatic image carrier. -1521 shows the relationship between surface potential and reflection density when DO and MuO bias are Ov, and curve 22 shows the relationship between Muo
It shows the relationship between surface potential and reflection density under an AC bias of 300V and frequency &150011Z. 23 shows the case where the reflection immersion degree of paper is O and OS for reference.

Without an alternating electric field, the toner conveyance speed is slow, which tends to cause uneven conveyance of the image, resulting in low sharpness and capri. When an alternating electric field is applied to this, the uneven conveyance of the image disappears, the sharpness improves, and the capri becomes Wk*.

There are limits to the magnitude and frequency of the alternating electric field for eliminating image unevenness, capri, and increasing sharpness, and we experimentally determined that an appropriate development area exists.

An example of area distribution is shown in jl13E. The dielectric breakdown region of the third WA is a region where dielectric breakdown occurs through the photoreceptor and toner layer when high voltage is applied. This region varies depending on the II chain and layer thickness of the photoreceptor layer.

Further, the capri generation area is an area where toner adheres to the non-image area. Needless to say, this capri generation region varies depending on the type and amount of magnetic material contained in the toner and the magnetic bias caused by the magnetic force within the sleeve. A low amphiphilic region is a region where the effect of the alternating electric field is weak (-) where the image becomes uneven or capricious, or where a sharp image cannot be obtained.

As described above, it has become clear that in the relationship between frequency and applied voltage, there is an appropriate region as shown in FIG. 3 in which good images can be obtained.

No. 411 shows another embodiment of the present invention. The difference from the first embodiment is that the distance between the electrostatic image holder 1 and the cylindrical sleeve 2 is 0.5 cm. Further, the second rotation speed of the cylindrical sleeve was set to 50 rPlm. The magnetic rolls 3 inside the cylindrical sleeve 2 are alternately magnetized to 900 Gauss, and thin plates are formed in the direction of the arrow ◎For toner! Insulating particles containing Dannetite by weight of 55%! And so. In addition, 10 as a DC bias power supply 12 is connected in series to the AC power supply 10.
0VIi degree was applied.

Under the above conditions, the development that takes place between the electrostatic image holder 1 and the cylindrical sleeve 2 that acts as a developing electrode and its effects are 511%
The first embodiment shown in the third cabinet and f
An appropriate region of Qllll was obtained. In the second embodiment shown in FIG. 5, the dielectric breakdown region is smaller than the third wJ, but
This is because the distance between the electrostatic image holder 1 and the cylindrical sleeve 2 is wider than in the first embodiment, and the amount of magnetic material contained in the toner is reduced.

As seen in the above embodiments, in a developing device that performs development by bringing a single layer of insulating toner into contact with an electrostatic image holding member having an electrostatic image charge, the effect of AC bias voltage application and low speed The stable development achieved by supplying toner can be thought of as follows.@ As shown in Figures 1 and 4, insulating toner is produced by the combination of magnetic force and electrostatic image charge on the cylindrical sleeve 2. Due to the difference with the Coulomb force, the toner is attracted toward the electrostatic image holder 19 and developed, but the toner that contributes to development is a part of the insulating toner layer that approaches the surface of the electrostatic image holder 1. It's toner. By applying an AC bias voltage, which is a superimposition of an AC voltage and a bias voltage, to the cylindrical sleeve 2 acting as a developing electrode, the insulating film is affected by this alternating electric field. Each time the direction in which this alternating electric field is applied changes, the direction of the force acting on the toner changes, and the toner moves in a corresponding direction.

At this time, since the toner is also affected by the charge of the electrostatic image 1'', the toner faithfully reproduces the electrostatic image.

The toner is vibrated by the AC bias voltage, and if there is not enough toner supply tray, more toner comes into contact with the surface of the electrostatic image carrier than if the AC bias voltage is not applied, resulting in more effective development. This is done in a consistent manner, resulting in a high-density image. On the other hand, when there is an excess of toner on the toner supply tray, stable development is performed because an appropriate amount of toner adheres, which is smaller than when no alternating current bias is applied. In addition, the non-image S&:@< attached sinner particles, which degrade the image, receive force from the alternating electric field and are thrown off or moved to a high electric field area.

Therefore, even if the toner is supplied at a low speed, it is possible to obtain a perfectly stable and highly sharp microscopic image.

The movement of the toner is different from the flying of the toner in the Janbinda method, and is characterized by the fact that the toner layer is in contact with the electrostatic image holder, and the distance required for the toner movement to sharpen the image is Since the toner particle size is substantially on the order of the order of magnitude, the characteristics required for the alternating electric field are limited to the jumping development conditions (JP-A-55-1) as shown in sWg or Figure 5.
61252).

It is necessary that a high alternating electric field can be applied to the insulating cinnabar particles, and the volume resistivity of the toner must be 101091 or more, preferably 1012 Ω or more.

The alternating electric field applied in the above embodiments may be a sine wave, a rectangular wave, a triangular wave, a toothed wave, or the like.

In the present invention, a frequency of 1 kHz or more can be used, but this is not preferable because of the power source and the use of high voltage. In the low frequency region, the moving speed of the electrostatic image holder is usually more than 100 cm/a.O.
Uniform development is not performed in the region below nzli degree. The preferred frequency range is 100HK N10 KH! It is. According to the experimental results, the effective frequency range for image sharpening is 100Hjli-10KHI 1m degree, especially for I
K to 5 KHz was preferable.

Further, in the above embodiment, a sine wave centered at OV was used, but an AC bias voltage having a DC component of, for example, about 200 mm may also be applied.

As explained above, the present invention uses insulating magnetic toner,
While supplying the toner to the electrostatic image holder at a low speed, an electric field is generated between the electrostatic image holder and the toner carrier under the magnetic force from the developer support, and the toner particles are transferred to the above holder. Shake by the electric field! Since this developing device accelerates development and prevents the toner from adhering to non-image areas on the electrostatic image holder, it eliminates sharp ruts while still taking advantage of the features of conventional contact development. It is possible to obtain a stable copy image.

In particular, the fact that the layer between toner aggregation is eliminated is
Taking into consideration the details, this means that a toner with a low softening point temperature or a toner with good fixing properties can be used, which is effective in relaxing the fixing conditions in a fixing device that uses heat or pressure. Furthermore, the driving force of the developing device can be lowered, which is effective in reducing heat generation and helps prevent toner agglomeration.

Although the cylindrical sleeve of the image agent carrier in the above embodiments was non-magnetic, the present invention can also be applied to cases where the sleeve is made of a magnetic material.

[Brief explanation of the drawing]

FIG. 1 and °$1411 are the first part of the present invention. This is a section F1 diagram showing the schematic structure of the second embodiment. FIG. 2 shows the relationship between the surface potential of the electrostatic image holder and the reflection loss of the image. This is a graph showing the results. l... Electrostatic image holder 2... Cylindrical sleeve 3... Magnet pole 4...
I & Reagent Supply Kanto 5...Replenishment Leela 6...
... True developer wealth 7 ... Screw S ... Developer thickness regulation blade 9 ... Cleaning blade 10 ... AC power supply agent Yoshikazu Kuwahara 'II! 11th table aoli, t(v) No. 5121 4R, llfil%K
(XI♂l-1,) Kawakumi Maki 1f) 5 Concavity Procedural Amendment Written by March 16th, 1983, Mr. Kazuo Wakasugi, Director-General of the Patent Office, Incident & Presentation Patent Application No. 208690, 1982, Title of the Invention My device 3 Relationship with the case of the person making the amendment Patent applicant address: 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo, Japan
Name (+27) Konishiroku Photo Industry Co., Ltd.? 1. For Representative Directors 5. Supplementary iE Life Insurance Day 1. Voluntary 6. Subject of amendment (1) “Drawing No. 2 )
r Detailed description of the invention in the specification" 7. Contents of the amendment (1) As per the amended appendix to the drawings. (11) As in the amended appendix to the scope of claims. It says "the same or".
Corrected. On page 6, line 11, it says "circumferential speeds of about the same degree" has been corrected to "circumferential speeds of about the same level or worse." $111, line 16, it says ``It's narrow, but'' it was corrected to ``It's spread out.'' Attached Claims (1) In a developing device that visualizes an electrostatic image by bringing an insulating magnetic thinner layer on a developer carrier into contact with an electrostatic image carrier, the developer carried by the insulating magnetic toner is provided. The developing device is configured such that the moving speed of the electrostatic image carrier is set to be substantially the same as or slower than the moving speed of the electrostatic image carrier, and at least an alternating current bias voltage is applied to the developer carrier. (2) The developing device according to claim 2I, paragraph 1, characterized in that an insulating magnetic toner having a volume resistivity of 10'·Ω1 or more is used. (3) The frequency of the above alternating electric field is 100Hm-1010O
H island 20 kfl house position (v)

Claims (1)

[Scope of Claims] (1) In a developing device that visualizes an electrostatic image by bringing a single layer of magnetic thinner on a developer carrier into contact with an electrostatic image carrier, a developer carrying the insulating magnetic toner is provided. Agent carrier-
is set to a speed that is the same as or slower than the moderate movement of the electrostatic image carrier, and at least an alternating current bias voltage is applied to the 1ulla developer carrier. 2. The developing device according to claim 1, wherein an insulating magnetic material having a volume resistivity of 1010 Ω or more is used. (3) The frequency of the above alternating electric field is 100Hz-]oK
A developing device according to any one of claims 1 to 2, characterized in that the developing device has a frequency of Hz.